Chromium yeast alleviates heat stress by improving antioxidant and immune function in Holstein mid-lactation dairy cows

Selenized non-Saccharomyces yeasts and their potential use in fish feed

Selenium (Se) is a vital trace element, essential for growth and other biological functions in fish. Its significance lies in its role as a fundamental component of selenoproteins, which are crucial for optimal functioning of the organism. The inclusion of Se in the diets of farmed animals, including fish, has proved invaluable in mitigating the challenges arising from elemental deficiencies experienced in captivity conditions due to limitations in the content of fishmeal. Supplementing diets with Se enhances physiological responses, particularly mitigates the effects of the continuous presence of environmental stress factors. Organic Se has been shown to have higher absorption rates and a greater impact on bioavailability and overall health than inorganic forms. A characteristic feature of yeasts is their rapid proliferation and growth, marked by efficient mineral assimilation. Most of the selenized yeasts currently available in the market, and used predominantly in animal production and aquaculture, are based on Saccharomyces cerevisiae, which contains selenomethionine (Se-Met). The object of this review is to highlight the importance of selenized yeasts. In addition, it presents metabolic and productive aspects of other yeast genera that are important potential sources of organic selenium. Some yeast strains discussed produce metabolites of interest such as lipids, pigments, and amino acids, which could have applications in aquaculture and further enrich their usefulness.

Strategic administration of antioxidant multiminerals and vitamins to transitional buffaloes augments antioxidant and udder defense mechanisms in early lactation

The aim of the study was to examine the effects of repeated administrations of antioxidant multiminerals and vitamins in transition buffaloes on udder defense mechanism, antioxidant activity and occurrence of intramammary infection (IMI) in early lactation period. Forty clinically healthy pregnant buffaloes were enrolled 45 days before expected date of calving and randomly allocated into five different supplementation groups (n = 8): only basal ration (control), vitamin E and selenium (VES), multiminerals (MM), ascorbic acid (AA) and chromium (Cr) picolinate in basal diet. The udder defense mechanism was monitored by measuring phagocytic activity (PA), myeloperoxidase (MPO) and nitric oxide (NO) productions in milk leukocytes, antioxidant activity was evaluated by measuring total antioxidant capacity (TAC) in plasma and occurrence of IMI was assessed by milk cytology, bacterial count in milk and visible clinical signs of udder until day 28 post-calving. The results showed that the VES and MM supplementations exhibited significantly higher PA, MPO and NO productions of milk leukocytes till first week of lactation whereas, elevated mean TAC in plasma was maintained from day -7 to 1 of calving in MM supplementation group as compared to control group. Statistically, no significant difference in occurrences of subclinical or clinical IMI was noted across the groups until four weeks of lactation. Taken together, it is concluded that repeated administrations of VES and MM to transition buffaloes could be an effective strategy to maintain good udder health by augmenting milk leukocyte functions and antioxidant status and preventing incidence of IMI in early lactation.

Chitosan Oligosaccharides Alleviate Heat-Stress-Induced Lipid Metabolism Disorders by Suppressing the Oxidative Stress and Inflammatory Response in the Liver of Broilers

Heat stress has been reported to induce hepatic oxidative stress and alter lipid metabolism and fat deposition in broilers. Chitosan oligosaccharides (COSs), a natural oligosaccharide, has anti-oxidant, anti-inflammatory, and lipid-lowering effects. This study is conducted to evaluate dietary COS supplementation on hepatic anti-oxidant capacity, inflammatory response, and lipid metabolism in heat-stressed broilers. The results indicate that heat-stress-induced poor (p < 0.05) growth performance and higher (p < 0.05) abdominal adiposity are alleviated by COS supplementation. Heat stress increases (p < 0.05) serum AST and ATL activity, serum and liver MDA, TG, TC, and LDL-C levels, and the expression of hepatic IL-1β, IL-6, SREBP-1c, ACC, and FAS, while it decreases (p < 0.05) serum SOD and CAT activity, liver GSH-Px and SOD activity, and the expression of hepatic Nrf2, GPX1, IL-10, MTTP, PPARα, and CPT1. Nevertheless, COS supplementation decreases (p < 0.05) serum AST and ATL activity, serum and liver MDA, TG, TC, and LDL-C levels, and the expression of hepatic IL-1β, IL-6, SREBP-1c, ACC, and FAS, while it increases (p < 0.05) serum SOD and CAT activity, liver GSH-Px activity, and the expression of hepatic Nrf2, CAT, IL-10, LPL, MTTP, PPARα, and CPT1. In conclusion, COS could alleviate heat-stress-induced lipid metabolism disorders by enhancing hepatic anti-oxidant and anti-inflammatory capacity.

Plasma metabolic profiling reveals that chromium yeast alleviates the negative effects of heat stress in mid-lactation dairy cows

Chromium yeast (CY) supplementation has the potential to alleviate the negative effects of heat stress in dairy cows, but the mechanism remains elusive. We aimed to identify the metabolic mechanisms whereby CY supplementation alleviates the negative effects of heat stress in mid-lactation dairy cows. Twelve Holstein dairy cows with similar milk yield (24.6 ± 1.5 kg/d), parity (2 or 3) and days in milk (125 ± 8 d) were fed the same basal diet containing 0.09 mg of Cr/kg DM. They were allocated randomly to 2 groups: a control group (CON, without CY supplementation) and a CY group (CY, administered 0.36 mg Cr/kg DM). The experiment was performed over 8 weeks during a hot summer, in which the mean temperature-humidity index was 79.0 ± 3.13 (>72), indicating that the dairy cows were exposed to heat stress. Chromium yeast supplementation reduced rectal temperature (P = 0.032), and increased the lactation performance by increasing the yield of milk (+2.6 kg/d), protein, lactose and total solid, and protein and lactose percentages in the milk of the heat-stressed dairy cows (P < 0.05). Supplementation with CY increased the serum glucose and thyroxine concentrations, but reduced the urea nitrogen, insulin, and triiodothyronine concentrations on d 56 (P < 0.05). Furthermore, plasma metabolomic analysis was performed using liquid chromatography tandem-mass spectrometry, which identified 385 metabolites in the two groups. Subsequently, 16 significantly different metabolites in the plasma, were significantly higher in the CY group (variable importance for the projection >1.0, P < 0.05), and found to be involved in 6 Kyoto Encyclopedia of Genes and Genomes pathways, including those involved in nicotinate and nicotinamide metabolism. Specifically, plasma concentration of nicotinamide was higher after CY supplementation, which might also contribute to the reduction of rectal temperature, the regulation of glucose homeostasis, and an improvement in the lactation performance of heat-stressed dairy cows. In conclusion, CY supplementation reduces rectal temperature, influences metabolism by reducing serum insulin concentration and increasing serum glucose and plasma nicotinamide concentrations, and finally increases lactation performance of heat-stressed dairy cows.

Modeling the effects of heat stress in animal performance and enteric methane emissions in lactating dairy cows

Heat stress (HS) negatively affects dry matter intake (DMI), milk yield (MY), feed efficiency (FE), and free water intake (FWI) in dairy cows, with detrimental consequences to animal welfare, health, and profitability of dairy farms. Absolute enteric methane (CH₄) emission, yield (CH₄/DMI), and intensity (CH₄/MY) may also be affected. Therefore, the goal of this study was to model the changes in dairy cow productivity, water intake, and absolute CH₄ emissions, yield, and intensity with the progression (days of exposure) of a cyclical HS period in lactating dairy cows. Heat stress was induced by increasing the average temperature by 15°C (from 19°C in the thermoneutral period to 34°C) while keeping relative humidity constant at 20% (temperature-humidity index peaks of approximately 83) in climate-controlled chambers for up to 20 d. A database composed of individual records (n = 1,675) of DMI and MY from 82 heat-stressed lactating dairy cows housed in environmental chambers from 6 studies was used. Free water intake was also estimated based on DMI, dry matter, crude protein, sodium, and potassium content of the diets, and ambient temperature. Absolute CH₄ emissions was estimated based on DMI, fatty acids, and dietary digestible neutral detergent fiber content of the diets. Generalized additive mixed-effects models were used to describe the relationships of DMI, MY, FE, and absolute CH₄ emissions, yield, and intensity with HS. Dry matter intake and absolute CH₄ emissions and yield reduced with the progression of HS up to 9 d, when it started to increase again up to 20 d. Milk yield and FE reduced with the progression of HS up to 20 d. Free water intake (kg/d) decreased during the exposure to HS mainly because of a reduction in DMI; however, when expressed in kg/kg of DMI it increased modestly. Methane intensity also reduced initially up to d 5 during HS exposure but then started to increase again following the DMI and MY pattern up to d 20. However, the reductions in CH₄ emissions (absolute, yield, and intensity) occurred at the expense of decreases in DMI, MY, and FE, which are not desirable. This study provides quantitative predictions of the changes in animal performance (DMI, MY, FE, FWI) and CH₄ emissions (absolute, yield, and intensity) with the progression of HS in lactating dairy cows. The models developed in this study could be used as a tool to help dairy nutritionists to decide when and how to adopt strategies to mitigate the negative effects of HS on animal health and performance and related environmental costs. Thus, more precise and accurate on-farm management decisions could be taken with the use of these models. However, application of the developed models outside of the ranges of temperature-humidity index and period of HS exposure included in this study is not recommended. Also, validation of predictive capacity of the models to predict CH₄ emissions and FWI using data from in vivo studies where these variables are measured in heat-stressed lactating dairy cows is required before these models can be used.

Effects of dietary chromium supplementation on dry matter intake and milk production and composition in lactating dairy cows: A meta-analysis

Introduction

Chromium (Cr) is an essential mineral that has been demonstrated to enhance milk production in dairy cows. This study aims to evaluate the effects of dietary Cr supplementation on dry matter intake (DMI), milk production and composition using a meta-analysis based on existing literature.

Methods

A random effects meta-analysis was performed to investigate the effects of dietary Cr supplementation on DMI, milk production and composition. The heterogeneity was assessed using the I 2 statistic and Q test, while Egger's test was used to evaluate publication bias.

Results

The meta-analysis discovered that Cr-supplemented cows had a significantly higher DMI compared to those not supplemented, with an increase of 0.72 kg/day [95% confidence interval (CI), 0.46-0.97]. The regression model indicated that DMI significantly increased by 0.9 g/kg of body weight (BW) and by 80.5 g for an increase of 1 mg of Cr supplement. The supplementation phase was associated with an increase in DMI, with an increase of 0.4582 kg/day for BFP (before parturition) and 0.853 kg/day for AFP (after parturition). The methionine and yeast forms of Cr increased DMI by 0.714 and 1.137 kg/day, respectively. The DMI was increased by 2.137 and 0.620 kg/day for multiparous (MP)+ primiparous (PP) cows and MP cows, respectively. Milk production was also increased by Cr supplementation, with an increase of 1.20 kg/day (95% CI, 0.65-1.76). The regression model indicated that milk production increased by 2.3 g/day for an increase of 1 kg of BW and by 122.4 g/day for an increase of 1 mg of Cr supplement. Milk production also increased with the duration of the experiment and days in milk. The amino acid and methionine forms of Cr complexes increased milk production by 1.645 and 1.448 kg/day, respectively. Milk production increased by 1.087 and 1.920 kg/day for MP and PP cows, respectively. Milk composition was not significantly affected by Cr supplementation. Egger's test for publication biases was not significant for all responses of interest.

Discussion

The meta-analysis showed that Cr supplementation improves DMI and milk production in dairy cows. The results suggest that the supplementation phase, form of Cr, and parity should be considered when supplementing dairy cows with Cr. The results have important implications for the dairy industry and can contribute to the development of more effective feeding strategies for dairy cows.

Effects of Organic Chromium Yeast on Performance, Meat Quality, and Serum Parameters of Grow-Finish Pigs

Trivalent chromium (Cr) is an essential trace element for humans and animals. This study was conducted to investigate the effects of chromium(III) yeast (CrYst) on growth performance, carcass characteristics, meat traits, antioxidant status, immune traits, and serum biochemical parameters of grow-finish pigs. A total of 72 commercial hybrid barrows (Duroc × Landrace × Large White) of approximately 50 kg body weight were allocated into two dietary treatments randomly, which received a corn-soybean meal basal diet or a basal diet supplemented with 100 mg CrYst/kg. The trial duration was 11 weeks divided into three periods from body weights of 50-75 kg, 75-100 kg, and 100-110 kg, respectively. The results revealed that supplemental CrYst did not affect growth performance. Organic CrYst supplementation significantly decreased the backfat depth and increased the meat tenderness score and juiciness score values in pigs (P < 0.05), while other carcass traits and meat traits indexes were unaffected. CrYst addition significantly decreased serum malondialdehyde (MDA) content of pigs in the whole growth phase; significantly increased the serum levels of immunoglobulin G (IgG), total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px), and reduced glutathione (GSH) in growing pigs; and also increased the serum IgG, IgM, and GSH concentrations in pigs during the finishing phase (P < 0.05). Additionally, diets supplemented with CrYst significantly decreased the serum high-density lipoprotein cholesterol (HDL-C) content in growing pigs and significantly increased the serum LDL-C level at the fattening period (P < 0.05), whereas no significant differences were observed for the other serum biochemical indexes compared to the control pigs. In conclusion, CrYst supplementation could reduce lipid peroxidation and backfat thickness and improve the meat tenderness and juiciness, immune traits, and antioxidant status of pigs.

Dietary supplementation with synbiotics improves growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress

This study investigated the effects of synbiotics supplementation on growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress. One hundred and forty-four 22-day-old male broilers were randomly assigned to one of three treatment groups of six replicates each for a 21-day study, with eight birds per replicate. Broilers in the control group were reared at a thermoneutral temperature and received a basal diet. Broilers in the other two heat-stressed groups were fed a basal diet supplemented without (heat-stressed group) and with 1.5 g/kg synbiotic (synbiotic group). One and a half gram of the synbiotic consisted with 3 × 10⁹ colony forming units (CFU) Clostridium butyricum, 1.5 × 10⁹ CFU Bacillus licheniformis, 4.5 × 10¹⁰ CFU Bacillus subtilis, 600 mg yeast cell wall, and 150 mg xylooligosaccharide. Compared with the control group, heat stress increased rectal temperatures at 28, 35, and 42 days of age, respectively (P < 0.05). Birds subjected to heat stress had reduced weight gain, feed intake, and feed efficiency during 22 to 42 days (P < 0.05). In contrast, supplementation with the synbiotic decreased rectal temperature at 42 days of age and elevated weight gain of heat stress-challenged broilers (P < 0.05). Heat-stressed broilers exhibited a lower superoxide dismutase (SOD) activity in jejunal mucosa and a higher malondialdehyde accumulation in serum, liver and jejunal mucosa (P < 0.05), and the regressive SOD activity was normalized to control level when supplementing synbiotic (P < 0.05). Heat stress increased interleukin-1β (IL-1β) and interferon-γ (IFN-γ) levels in serum and IL-1β content in jejunal mucosa of broilers (P < 0.05). Synbiotic reduced IL-1β level in serum of broilers subjected to heat stress (P < 0.05). Compared with the control group, elevated serum diamine oxidase activity and reduced jejunal villus height were observed in broilers of the heat-stressed group (P < 0.05), and the values of these two parameters in the synbiotic group were intermediate (P > 0.05). Heat stress upregulated mRNA abundance of IL-1β and IFN-γ and downregulated gene expression levels of occluding and zonula occluden-1 (ZO-1) in jejunal mucosa of broilers (P < 0.05). The alterations in the mRNA expression levels of jejunal IL-1β and ZO-1 were reversed by the synbiotic (P > 0.05). In conclusion, dietary synbiotics could improve growth performance, antioxidant capacity, immune function, and intestinal barrier function in heat-stressed broilers.

Dietary Supplemental Chromium Yeast Improved the Antioxidant Capacity, Immunity and Liver Health in Broilers under High Stocking Density

This study was conducted to investigate the effects of different levels of yeast chromium on growth performance, organ index, antioxidant capacity, immune performance and liver health of broilers under high stocking density. A total of 684 1-day-old Arbor Acres broilers were selected and fed a common diet from 1 to 22 days of age. At the end of 22 days, broilers with similar weight were randomly divided into six treatments, with six replications in each treatment. The broilers in control groups were fed with a control diet and raised at low stocking density of broilers (14 broilers/m2, LSD) and high stocking density (20 broilers/m2, HSD). The broilers in treatment groups were fed with diets supplemented with 200, 400, 800 and 1600 µg Cr/kg chromium yeast (Cr-yeast) under HSD, respectively. The experimental period was 23~42 days. Compared with the LSD group, the HSD group significantly decreased the liver index (ratio of liver weight to live weight of broilers) of broilers (p < 0.05), the HSD group significantly increased the content of corticosterone (CORT) and the activities of alanine aminotransferase (ALT) and alkaline phosphatase (ALP) and decreased the prealbumin (PA) level in the serum (p < 0.05). HSD decreased the total antioxidant capacity (T-AOC) contents in the serum, liver and breast, serum glutathione peroxidase (GSH-Px) activities, breast total superoxide dismutase (T-SOD) activities and liver catalase (CAT) activities of broilers (p < 0.05). The HSD group significantly increased the total histopathological score (p < 0.05). Compared with the HSD group, adding 200, 400, and 1600 Cr-yeast significantly increased the liver index of broilers (p < 0.05), all HSD + Cr-yeast groups decreased the ALT activities (p < 0.05), and the HSD + 800 group significantly decreased the CORT contents and the ALP activities of the serum (p < 0.05); the HSD + 400, 800 and 1600 groups increased the PA contents of the serum (p < 0.05); HSD + 800 group significantly reduced the tumor necrosis factor-α (TNF-α) and Interleukin-1β (IL-1β) contents of the serum (p < 0.05); moreover, the HSD + 400 group increased the GSH-Px activities of the serum (p < 0.05), the T-AOC and the T-SOD activities of the breast (p < 0.05) and the T-AOC and CAT activities of the liver (p < 0.05). Adding 800 Cr-yeast significantly decreased the total histopathological score (degree of hepatocyte edema and inflammatory cell infiltration) under HSD (p < 0.05). In summary, Cr-yeast can improve the antioxidant capacity and immune traits, and liver health of broilers under HSD. Based on the results of the linear regression analysis, the optimal supplementation of Cr-yeast in antioxidant capacity, immunity ability and liver health were at the range of 425.00−665.00, 319.30−961.00, and 800.00−1531.60 µg Cr/kg, respectively.

Effects of Saccharomyces Cerevisiae Cultures on Performance and Immune Performance of Dairy Cows During Heat Stress

The dairy farming industry is facing massive economic losses as heat stress continues to rise. The purpose of this study was to see how feeding Saccharomyces cerevisiae culture (SC) influences productive performance, lactation performance, serum biochemical indexes, hormonal level, antioxidant capacity, and immune function in mid-lactating cows during heat stress. Forty-five healthy mid-lactation dairy cows with comparable milk yield, lactation days, and parity were randomly divided into 3 groups (15 cows in each group). The control group (CON) was fed the basal diet, while the treatment groups were fed the basal diet + first Saccharomyces cerevisiae culture 100 g/d (SC-1) and the basal diet + second Saccharomyces cerevisiae culture 30 g/d (SC-2), respectively. The SC-1 and SC-2 groups with SC added in the treatment groups reduced rectal temperature and respiratory rate in heat-stressed cows (P &lt; 0.05). The milk yield of SC-1 and SC-2 treatment groups was significantly higher than that of CON (P &lt; 0.05). Except for somatic cell count, which was significantly lower in SC-1 and SC-2 than in CON (P &lt; 0.05), there were no significant differences in the milk components. The addition of SC: (i) increased serum urea levels (P &lt; 0.05), but there was no significant difference in glucose, total cholesterol, alanine transaminase, aspartate aminotransferase, total protein, albumin and alkaline phosphatase levels (P &gt; 0.05); (ii) increased serum levels of immunoglobulin-A, immunoglobulin-G, immunoglobulin M, interleukin-4, interleukin-10 and heat shock protein-70 (P &lt; 0.05), while decreasing serum levels of interleukin-1β, interleukin-6, interleukin-2, interferon-γ and tumor necrosis factor-α (P &lt; 0.05); (iii) increased total antioxidant capacity, glutathione peroxidase and superoxide dismutase in serum (P &lt; 0.05), while decreasing malondialdehyde; (iv) increased serum levels of glucocorticoids, insulin, cortisol and prolactin (P &lt; 0.05), while decreasing the serum levels of triiodothyronine and thyroxine (P &lt; 0.05). In conclusion, under the current experimental conditions, the addition of SC can reduce rectal temperature and respiratory rate in heat-stressed mid-lactation cows, reduce the number of somatic cells in milk and improve the mid-lactation cow performance. In addition, SC addition to the diet can raise serum urea levels, regulate serum hormone levels, boost antioxidant capacity in mid-lactation cows, and boost overall immunity.

Intestinal microbiomics and liver metabolomics insights into the preventive effects of chromium (III)-enriched yeast on hyperlipidemia and hyperglycemia induced by high-fat and high-fructose diet

In recent years, organic chromium (III) supplements have received increasing attentions for their low toxicity, high bioavailability and wide range of health-promoting benefits. This study aimed to investigate the preventive effects of chromium (III)-enriched yeast (YCr) on high-fat and high-fructose diet (HFHFD)-induced hyperlipidemia and hyperglycemia in mice, and further clarify its mechanism of action from the perspective of intestinal microbiomics and liver metabolomics. The results indicated that oral administration of YCr remarkably inhibited the aberrant elevations of body weight, blood glucose and lipid levels, hepatic cholesterol (TC) and triglyceride (TG) levels caused by HFHFD. Liver histological examination showed that oral YCr intervention inhibited HFHFD induced liver lipid accumulation. Besides, 16S rDNA amplicon sequencing showed that YCr intervention was beneficial to ameliorating intestinal microbiota dysbiosis by altering the proportion of some intestinal microbial phylotypes. Correlation-based network analysis indicated that the key intestinal microbial phylotypes intervened by YCr were closely related to some biochemical parameters associated with glucose and lipid metabolism. Liver metabolomics analysis revealed that dietary YCr intervention significantly regulated the levels of some biomarkers involved in purine metabolism, glycerophospholipid metabolism, citrate cycle, pyrimidine metabolism, glycerophospholipid metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, and so on. Moreover, dietary YCr intervention regulated the mRNA levels of key genes associated with glucose, cholesterol, fatty acids and bile acids metabolism in liver. These findings suggest that dietary YCr intervention has beneficial effects on glucose and lipid metabolism by regulating intestinal microbiota and liver metabolic pathway, and thus can be served as a functional component to prevent hyperlipidemia and hyperglycemia.

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Chromium-enriched yeast enhances glucose tolerance and liver glycogen synthesis.

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Chromium-enriched yeast ameliorates the disturbance of intestinal microbiota.

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Explore the hepatoprotective effect of chromium-enriched yeast based on metabolomics.

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Chromium-enriched yeast alleviates lipid metabolism through “gut-liver” axis.

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Chromium-enriched yeast intervention affects hepatic gene transcription levels.

The role of dietary chromium supplementation in relieving heat stress of juvenile blunt snout bream Megalobrama amblycephala

The present study assessed the role of dietary chromium (Cr) supplementation in relieving heat stress (HS) of juvenile blunt snout bream Megalobrama amblycephala. The supplemented Cr contents by chromium picolinate (Cr-Pic) was 0 mg/kg (control group), 0.4 mg/kg, 1.6 mg/kg and 12.0 mg/kg, respectively. The fish continued to be fed four diets at suitable temperatures (26 °C) for 2 weeks, and then the temperature was then heated up to 33 °C through thermo-regulated system. The results showed that Cr supplementation had no significant effect on the immune indices and antioxidant indices before HS (P > 0.05). However, Cr supplementation played an important role in relieving HS. After HS, compared with the control group, 1.6 mg/kg and 12.0 mg/kg Cr supplementation groups significantly lowered the plasma glucose level and aspartate transaminase (AST) activity (P < 0.05), and 0.4 mg/kg and 1.6 mg/kg Cr supplementation groups significantly lowered alanine aminotransferase (ALT) activity (P < 0.05). 0.4 mg/kg and 1.6 mg/kg supplementation groups significantly improved hepatic total superoxide dismutase (T-SOD) activity (P < 0.05). Furthermore, 0.4mg/kg-12.0 mg/kg Cr supplementation groups significantly improved the activities of hepatic glutathione peroxidase (GPx) and catalase (CAT) and lowered hepatic malondialdehyde (MDA) level in liver (P < 0.05). The mRNA levels of hepatic copper zinc superoxide dismutase (Cu/Zn-SOD), CAT and GPx were significantly improved in 0.4mg/kg-12.0 mg/kg supplementation Cr groups (P < 0.05), however, there was no significant variation of hepatic manganese superoxide dismutase (Mn-SOD) mRNA levels under different levels of supplementation (P > 0.05). Significantly lower mRNA levels of hepatic pro-inflammatory cytokines observed in 0.4mg/kg-12.0 mg/kg Cr supplementation groups including tumour necrosis factor-α (TNF-α), interleukin 1β (IL-1β) and interleukin 8 (IL-8) (P < 0.05), and 0.4mg/kg-12.0 mg/kg Cr supplementation significantly improved the relative expressions of hepatic heat shock protein 70 (HSP70) and heat shock protein 90 (HSP90) (P < 0.05). The present study indicated that dietary Cr supplementation might have no significant effect on immune capacity and antioxidant capacity under normal physiological conditions, whereas it played an important role in relieving HS.

Optimizing the growth and immune system of dairy calves by subdividing the pre-weaning period and providing different milk volumes for each stage

In systematically considering the advantages and disadvantages of complementarity in high or low milk feeding, novel milk feeding schemes involving altering the volume of supplied milk in different stages of the pre-weaning period but maintaining the total milk feeding volume were tested. Twenty-seven newborn male Holstein calves were selected and randomly assigned to 3 treatments. Calves in the control (CON) group were fed 7 L of milk daily from 4 to 66 d of age. Calves in the low-high (LH) group were fed 6 L of milk daily at the beginning, and then the daily feeding volume was later increased to 7 to 8 L of milk, which served as the early-period low-volume feeding group. The calves in the high-low (HL) group were fed 7 to 8 L daily at the beginning, and then the daily feeding volume was decreased to 6 L of milk, which served as the early-period high-volume feeding group. Then all calves were fed 3 L of milk daily from 67 to 70 d of age, weaned at 70 d of age, and then fed starter feed to 100 d of age. All calves had access to the starter feed from 15 to 100 d of age. The diarrheal condition of calves was recorded daily and the growth performance including the starter feed intake and body weight of calves was recorded at 70 and 100 d of age. Then, five 100-d-old calves from each treatment were sampled for measurement of plasma indices, ruminal morphology, and volatile fatty acids. When compared with the CON and LH groups, calves in the HL group exhibited a significantly increased body weight and lower diarrhoeal rate. When compared with the CON group, calves in the HL group exhibited a significantly increased average daily feed intake, ruminal epithelium papillae length, total volatile fatty acids, and percentages of propionate and butyrate. Moreover, the significantly increased plasma immunoglobulin G (IgG) content and a trend of decreased tumor necrosis factor-α (TNF-α) content (P = 0.083) were also identified in the HL group when compared with the CON group. Overall, the early-period high-volume feeding for calves produced greater body weight gain and a lower incidence of diarrhea.

The effects of heat stress on the behaviour of dairy cows – a review

Heat stress in livestock is a function of macro- and microclimatic factors, their duration and intensity, the environments where they occur and the biological characteristics of the animal. Due to intense metabolic processes, high-producing dairy cows are highly vulnerable to the effects of heat stress. Disturbances in their thermoregulatory capability are reflected by behavioural, physiological and production changes. Expression of thermoregulatory behaviour such as reduction of activity and feed intake, searching for a cooler places or disturbances in reproductive behaviours may be very important indicators of animal welfare. Especially maintain of standing or lying position in dairy cattle may be a valuable marker of the negative environmental impact. Highly mechanized farms with large numbers of animals have the informatic system can detect alterations automatically, while small family farms cannot afford these type of equipments. Therefore, observing and analysing behavioural changes to achieve a greater understanding of heat stress issue may be a key factor for developing the effective strategies to minimize the effects of heat stress in cattle. The aim of this review is to present the state of knowledge, over the last years, regarding behavioural changes in dairy cows (Bos Taurus) exposed to heat stress conditions and discuss some herd management strategies provided mitigation of the overheat consequences.